This invention relates to a method and mechanism for driving optical members in an optical apparatus such as a camera, enlarger, printer, etc. and more particularly to such method and mechanism suitable for the purpose of moving a lens along an optical axis or adjusting a diaphragm stop.
FIG. 7 of the accompanying drawings is a sectional view schematically illustrating a construction of a conventional driving mechanism for an enlarging lens 1 and an iris diaphragm 2, both of which are important optical members constituting the optical enlarger in an automatic printer. Enlarging lens 1 is movable along its optical axis S for power variation or focussing. Iris diaphragm 2 lies midway between axially opposite ends of enlarging lens 1, so that iris diaphragm 2 may be driven in the direction of iris-in or iris-on as diaphragm pins 2a operatively associated with iris diaphragm 2 are rotated around the optical axis S.
There is provided a driving plate 3 extending in parallel to the optical axis S and formed with driving slits 3a, which have their longitudinal direction in parallel to the optical axis S. Diaphragm pins 2a of iris diaphragm 2 are normally in loose engagement with driving slits 3a. Driving plate 3 is fixed to an inner peripheral surface of an annular driving ring 4. Driving ring 4 is rotatable along an inner peripheral surface of a lens barrel 5 stationarily mounted on an apparatus frame and provided with a driving pin 4a mounted thereon. Driving pin 4a is oriented outward of driving ring 4 on one hand, and lens barrel 5 is partially formed with a slit 5a which extends circumferentially of lens barrel 5 on the other hand. Driving pin 4a is inserted into this slit 5a. An annular diaphragm driving gear 6 adapted to be rotated along an outer peripheral surface of lens barrel 5 is fixed to a distal end of driving pin 4a projecting outward beyond lens barrel 5. Diaphragm driving gear 6 is operatively associated via an appropriate gear train with an output shaft of a diaphragm driving motor 8, so that the output rotation of diaphragm driving motor 8 may be transmitted to diaphragm driving gear 6.
A lens driving pin 10a is provided on a lens mount 10 which holds, in turn, enlarging lens 1 and extends radially outward of mount 10. Lens barrel 5 is partially formed with a guide slit 5b having its longitudinal direction in parallel to the optical axis S, so that lens driving pin 10a may extend outward through guide slit 5b beyond lens barrel 5. A cylinder cam 12 adapted to be rotated around the optical axis S is provided on the outer peripheral surface of lens barrel 5. Cylinder cam 12 is formed with an appropriately configured cam slit into which a distal end of lens driving pin 10a is inserted. An annular end of cylinder cam 12 is provided with an annular lens driving gear 13 fixed thereto, so that said lens driving gear 13 may be operatively associated via an appropriate gear train 14 with an output shaft of a lens driving motor 15.
Upon actuation of lens driving motor 15, the output rotation thereof is transmitted via gear train 14 to lens driving gear 13, and thereby cylinder cam 12 is rotated around the optical axis S. Lens driving pin 10a, having its distal end inserted into the cam slit of cylinder cam 12, extends through guide slit 5b of lens barrel 5. Therefore, lens driving pin 10a is prevented from rotating around the optical axis S, and lens driving pin 10a is guided by the cam slit so as to move along the optical axis S. Since lens driving pin 10a is mounted to lens mount 10, enlarging lens 1, held by lens mount 10, may be moved back and forth along the optical axis S to achieve desired power variation or focussing.
Diaphragm pin 2a moves back and forth along driving slit 3a as enlarging lens 1 moves back and forth without operative dissociation between diaphragm pin 2a and driving plate 3. Upon actuation of diaphragm driving motor 8, the output rotation thereof is transmitted via gear train 7 to diaphragm driving gear 6 so that driving ring 4 operatively associated with diaphragm driving gear 6 is rotated around the optical axis S. Rotation of the driving ring 4 causes driving plate 3 and thereby diaphragm pin 2a also to be rotated around the optical axis S. As a result, iris diaphragm 2 is driven in the direction of iris-in or iris-out, depending on the direction in which diaphragm pin 2a is rotated.
The optical member driving mechanism of the prior art as described above includes two separately provided motors, i.e., lens driving motor 15 exclusively used to drive enlarging lens 1 and diaphragm driving motor 8 exclusively used to drive iris diaphragm 2. These two motors respectively used to drive two different optical members must be incorporated within one and the same optical apparatus, almost inevitably making the optical apparatus bulky. In addition, the respective motors each have parts operatively associated with the respective optical members. Consequently, the number of parts correspondingly increases and the construction is correspondingly complicated. Furthermore, the weight of the optical apparatus also increases. As a result, the degree of freedom to select a space for installation of the optical apparatus is liable to be limited by these factors.